message - unable to load ISProd

I have been using Norton Internet Security for years.  I had the 2007, updated to 08 6 months ago 09.  I started my computer this afternoon and received a message that norton could not load ISProd.  I have never received he message before.  there is a link to the message that goes to the website and wants to download a tool. however when i do this nothing happens.  help!!